FIG. 1 is a block diagram showing a structure of a conventional distance ranging apparatus using an ultra-wideband (UWB) communication. The apparatus shown in FIG. 1 shows a structure of the distance ranging apparatus for a UWB radio.
A transmitted signal goes through a UWB antenna 101 and a band-pass filter 102 filters an output a signal form the UBW antenna 101 and outputs a filtered signal. Subsequently, a UWB signal receiver 103 such as a UWB coherent receiver and a UWB noncoherent receiver demodulates a signal modulated in a transmitting part from an output signal of the band-pass filter 102 and an analog to digital converter (ADC) 104 converts the demodulated signal into a digital signal. When the digital signal is acquired by the ADC 104, sampling information on a frame defining a section where data are physically transmitted is acquired. A frame adder 105 adds the sampled data through many frames, thereby reducing noise components.
When the frame adder 105 adds many frames, a time of arrival (TOA) estimator 106 calculates energy of the signal accumulating the frames and detects a maximum value of the calculated energy through first and second image signal processes. The TOA estimator 106 ranges a distance by detecting TOA when the maximum value of the energy is detected.
As described above, the conventional distance ranging apparatus is a system for applying diverse techniques to find a proper threshold in a time area. Therefore, there is a problem that resolution in distance ranging is largely changed according to the threshold set up to find a point at which the transmitted signal starts.
Since the conventional distance ranging apparatus is based on a time area signal process, noise or interference can affect on the distance ranging.